The sound is 100% vintage authentic, and the NPN properties of the transistors makes it possible to power the circuit with modern, negative ground polarity, without the need for additional charge pump circuitry. This is a big advantage over vintage original PNP germanium pedals, which can be tricky to integrate in a modern pedalboard because of their reverse power polarity (positive ground). No need for an isolated power supply for the Purple Faze!
The new, revised version, coming in March 2022, adds a few modern improvements to the output section of the vintage circuit. First, we have added a recovery gain stage to make the pedal LOUD, and second, we have added an output buffer to ensure a consistent, high-quality output signal from the pedal. In the original vintage pedal, the level control was wired directly to the output jack, making the output impedance change with the level setting. Not good, really, so we fixed that. This addition to the vintage circuit in no way changes or degrades the sound and response of the fuzz effect, it just takes care that you are passing on a healthy signal to the next pedal in your signal chain, without loss of tone.
The extra loudness provided by the recovery gain stage makes it possible to push the input stage of a tube amp into natural overdrive, making some super smooth fuzz sounds possible - somthing that can not be done with the relatively weak vintage fuzz face pedal.
The Purple Faze is mechanical true bypass, so the output buffer is only on, when the effect is on (no buffered bypass).
I personally match the germanium transistors for the Purple Faze, and pick them for high hfe (amplification factor) and low leakage. A great thing about the OC140 transistors is that they are not very leaky, and this is great for the fuzz face because it is by design a dark and mellow sounding circuit. Leakyness means loss of high frequencies, so picking transistors with low leakage makes for a brighter sounding pedal. Which is desirable for a fuzz face. If you ever tried one, and found it lifeless and boring sounding, chances are you played one with some super leaky PNP germaniums - which are the norm. The Purple Face is far more lively, exciting and inspiring than the average fuzz face based pedal. So don't be scared off by previous bad experiences with the fuzz face circuit. Done right, it's a magical thing (which I guess a certain mr. Hendrix proved very convincingly).
Reuss Purple Faze specifications: